(1) Field of the Invention
The present invention relates to a testosterone enhancer. In particular, the present invention relates to a composition that increases endogenous testosterone.
(2) Description of Related Art
Testosterone, which is a type of androgenic hormone, widely contributes to muscle growth, cognitive functions, blood vessel flexibility, lipid metabolism, reproductive functions, and the like. Although testosterone secretion decreases with age, presence of endocrine disruptors also affects secretion. A recent DNA microarray analysis of germ-free rats in an extreme vitamin K deficient state suggests a possibility of menaquinone-4 contributing to testosterone biosynthesis (8th Vitamin K and Bone Meeting Records, pages 87 to 89, Dec. 10, 2005, Eisai Co., Ltd.; and Shirakawa, et al., Biochim. Biophys. Acta Vitamin K deficiency reduces testosterone production in the testis through down-regulation of the Cyp11a a cholesterol side chain cleavage enzyme in rats, ARTICLE In Press, Accepted Manuscript, Available online 6, Jun. 2006).
Indications show that, when testosterone secretion decreases, concentration and motivation decrease. Memory becomes poor, and strength, micturition, and male sexual functions also deteriorate. In recent years, patients suffering from male climacteric disorder have increased. In male climacteric disorder, blood testosterone level decreases as a result of hypogonadism, causing symptoms such as those described above.
One treatment for male climacteric disorder is hormone replacement therapy in which a patient is injected with testosterone formulas. However, the injection causes a rapid increase in the blood testosterone level and may actually cause illness. The rapid increase in hormone levels may cause adverse side effects affecting the prostrate, blood vessels, liver, lungs, and the like. Therefore, the hormone replacement therapy sometimes uses a transdermal skin patch through which testosterone is slowly released.
In addition to testosterone being replaced from outside as described above, following methods are proposed to boost the testosterone level in the body: intake of benzyl glucosinolates and benzyl isothiocyanates found in maca and the like (Japanese Patent Application Laid-open No. 2005-306754); intake of a mixture of maca and antlers (Japanese Patent Application Laid-open No. 2003-523945); and intake of substituted pyrazole compounds (Japanese Patent Application Laid-open No. 2005-504093).